DEAD SEA, Jordan — Hoping to use economic promise as a bridge to a peace deal between Palestinians and Israel, Secretary of State John F. Kerry announced an estimated $4 billion economic development proposal for the West Bank on Sunday that he said could cut the 21 percent unemployment rate by two-thirds.

‘‘The greatest existential threat and the greatest economic threat to both sides is the lack of peace,’’ Kerry said. ‘‘To not try to head these off would be tragic, and it would be irresponsible.’’

International business leaders rallied by former prime minister Tony Blair of Britain will propose new agricultural, construction, and other investments to the Palestinian Authority that could increase the Palestinian gross domestic product by 50 percent over three years, Kerry said.

The State Department would not identify participating companies or provide other details about the content or timing of individual proposed investments.

Kerry addressed a World Economic Forum meeting after speeches by the Palestinian Authority president, Mahmoud Abbas, and President Shimon Peres of Israel.

The gathering on the shores of the Dead Sea in Jordan included a rare direct meeting between Israeli and Palestinian leaders, although Prime Minister Benjamin Netanyahu of Israel did not attend. In his remarks, Peres urged the two sides to overcome their differences and resume peace negotiations, saying neither the Israelis nor the Palestinians could afford “to lose this opportunity.’’

Kerry said improving lives and expectations for Palestinians, many of them young and underemployed, is key to building an independent Palestinian state at peace with neighboring Israel, and there is no time to waste.

Kerry offered no specifics on the economic program but said it would focus on jobs and tourism. Blair and Tim Collins, a billionaire investor and a friend of Kerry’s, recruited business leaders over the past six weeks as Kerry tried to nudge the two sides back to direct peace talks, which have been mostly stalled for five years.

‘‘Negotiations can’t succeed if you don’t negotiate,’’ Kerry said Sunday.

Peres and Abbas both thanked Kerry for his efforts and pledged willingness to make peace, prompting Kerry to respond, ‘‘I have an agreement here which you both can come up and sign — we’ll get there, we’ll get there.’’

Kerry has made restarting peace talks the main objective of his tenure as secretary of state, devoting much of the past three months to preparations that ask both sides to make good-faith concessions that would improve the atmosphere for talks. He said last week that his goal is talks without any preconditions, which he called the bane of past attempts.

Peres made a direct overture to Abbas, calling him Israel’s partner for peace.

In his remarks, Abbas appeared to remain skeptical of Israel’s intentions. He accused Israel of failing to seize the opportunity for peace presented by the 2002 Arab Peace Initiative, which Kerry is now using as a basis for new talks.

Abbas repeated that Palestinians will not accept ‘‘economic solutions’’ as a replacement for a free and sovereign country, nor would they accept ‘‘a temporary state, with temporary borders,’’ where Israel agrees to borders for 50 percent of Palestine with a promise to revisit the issue in 15 years.

Peres said he would not argue with Abbas nor debate the details from the stage.

Directing his remarks directly to Abbas, Peres said, ‘‘President Abbas, you are our partner, and we are yours.’’

He said all their differences are deeply moving and important, but he called on Abbas to sit down with the Israelis and negotiate. ‘‘You will be surprised how much can be achieved,’’ he said.

‘‘Skeptics don’t make history,’’ he added.

Peres applauded Kerry’s economic ideas as ‘‘imaginative’’ but agreed with Abbas that they were not a replacement for peace negotiations.

At the forum, a group of Israeli and Palestinian corporate leaders announced a business-led initiative called ‘‘Breaking the Impasse,’’ whose aim was to pressure their respective governments to pursue negotiations.

The group is led by a pair of billionaires, Israeli high-tech impresario Yossi Vardi and Palestinian ‘‘Duke of Nablus’’ Munib al-Masri, who made his first fortune in oil and gas and now runs a holding company.

BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.

Thanks & Welcome to Globe.com

You now have unlimited access for the next two weeks.

BostonGlobe.com complimentary digital access has been provided to you, without a subscription, for free starting today and ending in 14 days. After the free trial period, your free BostonGlobe.com digital access will stop immediately unless you sign up for BostonGlobe.com digital subscription. Current print and digital subscribers are not eligible for the free trial.